First few sponsors don't expect much, they might give you a little money in exchange for some PR stuff, but more or less it'll be really small stuff.
Try to avoid any extraneous binding contracts, no matter how good they seem at the time. eg: ' Wear ONLY so-and-so-inc outerwear for ALL competitions this year in exchange for 500$' , if you get popular and end up competing more at more important comps they will get way better PR for the same price
Finally expect to have to market the hell out of yourself. You should make a contact out of a representative within the sponsoring company and solely use them in regards to getting sponsored for anything. For every thing you get out of them you will have to continue to convince them its worth their time/money to continue to sponsor you. Need a new pair of skis? Expect to have to prove to them that you put in hours of research to determine the best possible option and demonstrate why. It will be an uphill battle for every little bit you get.